extract shared mosis-core library from sandbox APIs

Create core/ directory with platform-agnostic sandbox components:
- Timer manager, JSON API, Crypto API, Virtual FS
- Lua sandbox, Permission gate, Audit log, Rate limiter
- Platform abstraction interfaces (IAssetInterface, IFilesystemInterface)
- Platform-agnostic logger with Android/Desktop implementations

Update designer to link against mosis-core library instead of
including sandbox sources directly.

This is the foundation for unifying the Android service and
desktop designer to share the same codebase.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

core/include/mosis/sandbox/audit_log.h

@@ -0,0 +1,94 @@
+#pragma once
+
+#include <string>
+#include <vector>
+#include <mutex>
+#include <chrono>
+
+namespace mosis {
+
+enum class AuditEvent {
+    // Lifecycle
+    AppStart,
+    AppStop,
+
+    // Permissions
+    PermissionCheck,
+    PermissionGranted,
+    PermissionDenied,
+
+    // Network
+    NetworkRequest,
+    NetworkBlocked,
+
+    // Storage
+    FileAccess,
+    FileBlocked,
+    DatabaseAccess,
+
+    // Hardware
+    CameraAccess,
+    MicrophoneAccess,
+    LocationAccess,
+
+    // Security
+    SandboxViolation,
+    ResourceLimitHit,
+    RateLimitHit,
+
+    // Other
+    Custom
+};
+
+struct AuditEntry {
+    std::chrono::system_clock::time_point timestamp;
+    AuditEvent event;
+    std::string app_id;
+    std::string details;
+    bool success;
+};
+
+class AuditLog {
+public:
+    explicit AuditLog(size_t max_entries = 10000);
+
+    // Log an event
+    void Log(AuditEvent event, const std::string& app_id,
+             const std::string& details = "", bool success = true);
+
+    // Query entries (returns most recent first)
+    std::vector<AuditEntry> GetEntries(size_t count = 100) const;
+    std::vector<AuditEntry> GetEntriesForApp(const std::string& app_id,
+                                              size_t count = 100) const;
+    std::vector<AuditEntry> GetEntriesByEvent(AuditEvent event,
+                                               size_t count = 100) const;
+
+    // Statistics
+    size_t GetTotalEntries() const;
+    size_t GetStoredEntries() const;
+    size_t CountEvents(AuditEvent event, const std::string& app_id = "") const;
+
+    // Clear all entries
+    void Clear();
+
+    // Convert event to string for logging
+    static const char* EventToString(AuditEvent event);
+
+private:
+    mutable std::mutex m_mutex;
+    std::vector<AuditEntry> m_entries;
+    size_t m_max_entries;
+    size_t m_write_index = 0;
+    size_t m_total_logged = 0;
+    bool m_wrapped = false;
+};
+
+// Global audit log (singleton)
+AuditLog& GetAuditLog();
+
+} // namespace mosis
+
+// Convenience alias
+using AuditLog = mosis::AuditLog;
+using AuditEvent = mosis::AuditEvent;
+using AuditEntry = mosis::AuditEntry;